Ca3TaAl3Si2O14 (CTAS) piezoelectric powders were sintered at various temperatures to investigate phase formation. The CTAS powder sintered at 1350 °C was composed of a main phase with a langasite-type structure in addition to two secondary phases, whereas the main phases of the CTAS powders sintered at 1200 and 1300 °C were the secondary phases in X-ray diffraction patterns. CTAS single crystals with a diameter of 1 in. were grown by a Czochralski method using the sintered powders, and CTAS single crystals without impurity phases could be grown using the powder sintered at 1350 °C. A higher sintering temperature of starting materials contributes to the creation of CTAS single crystals without impurity phases.